Carbon frames on turbo trainers, chain length plus tyres and inner tubes – GCN Tech Clinic

From keeping a bike safe on a turbo trainer to the aerodynamics of valve cores, Alex Paton and Manon Lloyd are back in the studio to answer your tech quandaries in the latest GCN Tech Clinic.

If you’ve got a tech question that you need answering, don’t forget to leave it in a comment below one of our YouTube videos along with the hashtag #ASKGCNTECH.

Are steel frames more suitable than carbon frames for turbo trainers?

There are lots of myths about carbon frames breaking when attached to a turbo trainer. While there are real-life examples of this, they’re very rare and are usually linked to existing problems.

Turbo trainers are designed specifically to hold bikes of all shapes and sizes, regardless of the material, so you don’t need to avoid using a carbon frame. Just make sure the frame is mounted correctly so that the forces are evenly distributed across the frame.

Be wary of what your bike’s handbook says too, as some brands advise against using their bikes on turbo trainers, and it could invalidate your warranty.

• Read more: How to protect your bike while turbo training

Are shorter valves more aerodynamic than longer valves?

Yes!

But before you run to your local shop, the difference will be so minimal that you’re unlikely to even notice. If you're looking for more cheap and easy aero gains we have an article and video about that here.

How to calculate the correct chain length?

In an ideal world, you should keep your old chain and use this as a guide. That’s not always possible and we’ve all accidentally thrown things away before, but don’t worry!

It’s relatively easy to measure a chain. When in the smallest cog on the cassette and smallest chainring, the derailleur should take up the slack of the chain. You also need to make sure that the chain is long enough so that when you’re in the largest cog on the cassette and the largest ring, the derailleur still has a little bit of movement left in it.

Always shorten a chain incrementally, as it’s far easier to take some links off than add them back on.

Can you use a TPU inner tube with the Pirelli P Zero Race TLR Speedcore tyre?

For those unfamiliar, the Pirelli P Zero Race TLR Speedcore is a tubeless tyre, but it can also be used with an inner tube.

However, you will lose some of the advantages of the design, as the Speedcore liner is specifically designed for tubeless setups. This becomes redundant when running an inner tube.

Do oversized jockey wheels make cleaning easier?

Oversized jockey wheels are one of cycling’s many tech trends from the last few years, adopted as they theoretically make the drivetrain more efficient - but do they have another overlooked advantage of being easier to clean?

While the larger wheels should theoretically make things more accessible for cleaning, it’s an expensive change to make for very little return.

• Read more: How to clean your bike effectively in 5 minutes

Why aren’t puncture repair patches smaller?

If you’ve ever used a puncture repair patch, you may have noticed that they’re generally much larger than the punctures they’re covering.

This is because they need a contact area around the puncture to stick to. They’re also designed to cover a wide range of punctures, which won’t always be small pin-sized holes.

Do you need to compensate for tyre pressure lost when unplugging a pump from the valve?

When unplugging the pump from the tyre valve, you will lose a little bit of air, but this should only be a small amount.

It’s hard to measure how much pressure is lost, but if you’re concerned, you can pump your tyres up by a couple of extra PSI, which should be enough to cover the losses.

If you have any tech-related questions that you need answering, head over to this week’s Tech Clinic video on the GCN Tech YouTube channel and add your question to the comments along with #ASKGCNTECH. Or leave your question in the comments below.

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